I carried a .45 1911 for a long enough time, then switched to a polymer double-stack .45 (M&P and a XDM), and then eventually to a polymer double-stack 9mm (G17/G19). I have pondered the idea of going back to carrying a .45, and decided not to. I like my .45s, and I shoot them well, but for me it ultimately comes down to my wife's preferences. I can shoot 9mm or .45 about equally well, but my wife can't. I made a decision a little over a year ago to carry platforms that she was familiar with and could shoot well, in the event that she might end up having to shoot one of my guns. We both own G43s. Her's is her EDC. We both own G19s. Mine is my EDC. She is also able to shoot my G17 fairly well. So a 9mm Glock it is, and that is what we've "standardized" on.
I will say this..... there have been a few times when shooting at falling steel plates that one of my 9mm bullets has hit the plate square on, dead center, and failed to knock it over; but a hit from a .45 puts the plate down with authority. I have ended up trying to place my 9mm shots on the plate so as to maximize the amount of leverage the impact has against the hinge. You never have to do that with a .45. I am fairly certain that a couple of 230 grain HST JHPs at a muzzle velocity/energy of 890 fps/404 ft-lb will hit someone harder than a couple of 135 grain Critical Duty JHPs at 1010 fps/306 ft-lb.
But, that said, 9mm bullets have disabled and/or killed a LOT of people since George Luger first introduced the cartridge in 1902. Either cartridge is just fine for self-defense. I do understand why someone would feel more comfortable with one caliber over another, but the issue doesn't particularly bother me.